3/4 in IPS pipe insulation will also fit copper tubing with a nominal size of what?

• A. 1/2 in
• B. 3/4 in
• C. 1 in
• D. 1 1/4 in

Answer: (B)

The main idea is that insulation is sized by the pipe’s outside diameter (IPS). A sleeve labeled 3/4 in IPS is made to fit a pipe with an outside diameter of 7/8 in. Copper tubing uses nominal sizes, but the 3/4 in copper tubing has an outside diameter of 7/8 in, matching the 3/4 in IPS pipe. So the insulation will fit copper tubing with a nominal size of 3/4 in.

Other copper nominal sizes don’t fit because their outside diameters are different: 1/2 in copper is smaller (5/8 in OD), while 1 in and 1-1/4 in copper are larger (1-1/8 in and 1-5/8 in OD respectively).